MakerGear Forum

Aging of PETG Filament?

Aging of PETG Filament?

Posted: Thu Nov 02, 2017 4:15 pm

by Gwhite

Right after I got my M2E, I bought some Hatchbox white PETG in mid-summer, and used it for several weeks. I then sealed it up in a ziplock bag with desiccant and an indicator card. Yesterday I need to print a matching piece, and unpacked it. All the indicators (going down to 10%) were at least vaguely blue, so it should have been plenty dry.

I used exactly the same settings as before, but the resulting print showed serious under extrusion. Perimeter passes weren't touching in many places, and pinhole voids are visible in the top & bottom layers. Fortunately, it's not a critical application, and I can use it as is.

Is this a common problem? Even when sealed with desiccant, does filament tend to age that much, or should I be looking for another cause? Presumably it stores better in a vacuum, and I have some "space bags" I can use, but I'm sure that isn't as good a vacuum as what the factory uses.

If I need to recalibrate my extrusion multiplier every time I swap filaments (new or old), I need to factor that into my planning...

Thanks!

Re: Aging of PETG Filament?

Posted: Wed Nov 08, 2017 2:18 am

by jimc

thats prob not the issue. you could have the filament tension set too high which will cause you to squish the filament out of round and make it tight going through the filament path and extruder. can also be a partially clogged nozzle or the hot end is getting tight from buildup. this usually happens from having hot filament just sitting and cooking in the hot end. a cold pull using some nylon can help with that.

Re: Aging of PETG Filament?

Posted: Wed Nov 08, 2017 3:58 am

by Gwhite

I found that kicking the extrusion multiplier from 90 to 95 helped a little, but I had to adjust the restart distance & coast settings as well to largely eliminate the voids. It's still not perfect, but it was good enough, and I've had to switch filament for another job. The new filament is a regular PLA, and prints just like it did before, so I don't think my nozzle or drive are too far out of whack. I use eSun cleanign filament between materials, and that seems to do a pretty good job of getting the old stuff out.

Re: Aging of PETG Filament?

Posted: Sat Nov 18, 2017 2:32 pm

by willnewton

It is not uncommon to have an issue switching back to PLA from PETG. You may have a partial clog even with cleaning filament. It may work the first few times, but after a lot of switching, you may just need to pull the nozzle and torch it.

It could be a piece of PETG that has hardened or a bit of PLA that has burnt onto the nozzle.

If you don’t have a set of .35mm PCB end mills for cleaning your nozzle when it is hot, you should pick up a few. Be careful you don’t snap them off in the nozzle, they are delicate. They won’t solve every problem, but it does help.

Re: Aging of PETG Filament?

Posted: Sat Nov 18, 2017 2:55 pm

by Gwhite

I've been using the eSun Cleaning filament. Given that I've been working in different colors, I've been amazed at how much cleaning filament you need to run through to get the last vestiges of the old filament out. I had run some red PLA filament, and I gave the nozzle a very good cleaning. The cleaning filament was coming out it's normal cloudy white, but it's hard to see traces of color in the small extruded filament. The first print of white PETG came out ever so slightly pink...

Re: Aging of PETG Filament?

Posted: Tue Nov 28, 2017 6:45 pm

by zemlin

I print a lot of PETG, and have a couple rolls of color I rarely use. Never have any issue pulling them out for the occasional print. I have to agree with the others that it sounds more like a partial clog than a filament issue.

Re: Aging of PETG Filament?

Posted: Sun Mar 18, 2018 3:26 pm

by wmgeorge

I have some PETG that is maybe two years old, stored in the house and in sealed zip lock bags. How long are these good for and should I just test or toss?

Re: Aging of PETG Filament?

Posted: Mon Mar 19, 2018 2:58 pm

by sthone

I don't think you have to worry about PETG like you do with PLA. I have some that's probably older than that and it prints fine still.... just run it.